For years, doctors have been classifying people as obese based on their body mass index, which is determined by weight and height. But as many as half of patients with normal BMIs might still be “overfat,” meaning they have excess body fat that’s detrimental to their health — especially when it’s in the abdominal region.

You might be overfat if the circumference of your belly is larger than your hip circumference, the report states.

According to the research, being overfat is riskier than being merely overweight, because abdominal fat can lead to chronic illnesses such as diabetes, stroke, cancer, heart disease and inflammation.

A whopping 76 percent of the world’s population is overfat, according to the report. And that should be a huge wake-up call, says Louis Aronne, director of the Comprehensive Weight Control Center at Weill Cornell Medicine and NewYork-Presbyterian on the Upper East Side.

“We know that 11 cancers are related to obesity and 50 illnesses are a direct result of an increase in body fat,” says Aronne, who isn’t connected to the report. “So this is an obvious target for chronic disease management.”

But he says the best way to lose troubling belly fat is to cut back on sugar and starches, since those are prime culprits in stimulating insulin production, which can lead to more fat storage. Focus instead on consuming mostly vegetables and proteins.

Aronne also says that changing the order in which you consume foods — for instance, eating carbohydrates after protein and vegetables, instead of the other way around — can help your body metabolize food better.

And it’s best to adopt lifestyle habits that lower stress — and thus the hormone cortisol, which promotes fat storage in our abdomens as well, Aronne says.